This document was based on a document written by Bob Withers, bwit@pobox.com.
Additional information taken from documents written by Georg Rehfeld, rehfeld@wmd.de and David Mansfield, david@claremont.com.

My thanks go to the tremendous support from all the people involved in this document and the research that has gone into it. Particular thanks to Bob Withers and Mark Watling for the additional comments and help they have provided.